1. Technical Field of the Invention
The present invention relates generally to an alternator which may be installed in passenger automobiles or trucks, and more particularly to such an alternator having installed therein a heat dissipator which is equipped with heat dissipating fins.
2. Background Art
Typical automotive alternators are equipped with a rectifier which has a positive-side fin radiator and a negative-side fin radiator to cool rectifying devices installed on the positive-side and negative-side fin radiators. Japanese Patent Publication No. 3775235 teaches such fin radiators with circular or elongated holes which are formed by a press to increase heat dissipating area of the fin radiators. The air passes through the holes to cool the rectifying devices. Japanese Patent Publication No. 3707477 also discloses the fin radiators which are formed by the die-casting to have a plurality of sub-fins extending radially. The air passes between the sub-fins to cool the rectifying devices.
The structure of the fin radiators with the circular or elongated holes requires the need for increasing the distance between the holes due to geometrical limitations of press dies. It is, thus, difficult to have as large heat dissipating area as in the structure with the die-casted fin radiators, as taught in the latter publication. Too many circular or elongated holes will result in a decrease in thermal capacity of the fin radiators, which leads to a reduced ability to dissipate the heat. There is room for improvement in the former structure.
The structure of the fin radiators with the sub-fins faces the problem that burrs are formed between every adjacent two of the sub-fins or on portions of the sub-fins which are to be disposed between the dies. It is, thus, necessary to deburr the sub-fins, which results in an increase in production process and production cost. It is also necessary to accurately machine or cut holes in the fin radiators in which rectifying devices are to be press-fit, which will also contribute to an increase in production cost.